Muffler construction



March 26, 1940. B. B. CARY 2,194,457

MUFFLER CONSTRUCTION Filed July 27, 1938 2 Sheets-Sheet 1 l0 II II I! II H II lfl II II I] II II 1! mg! m 3mm- EE'ECHER E. CARY March 26, 1940. Y 2,194,457

IUFFLER CONSTRUCTION Filed July 2'7, 1938 2 Sheets-Sheet 2 Juvuowfoo EEECHEF? E. CARY Patented Mar. 26, 1940 2,194,451 MUFFLER CONSTRUCTION Beecher B. Cary, Jackson, Mich, assignor to Hayes Industries, Inc., Jackson, Mich., a corporation of Michigan Application July 27, 1938, Serial No. 221,472

2 Claims.

The present invention relates to improvements in muillers and the manufacture thereof and more particularly to mufflers for silencing the noises of the exhaust or intake of internal combustion engines.

Present day mufller constructions comprise for the most part an arrangement of tubular members, shells and baffles, forming resonating chambers having difierent characteristics for the 10 attenuation of different frequency tones found in the intake or exhaust gases, as the case may be. It has been heretofore proposed in making resonating chambers to simplify the manufacture of muiilers by stamping out two halves having necked portions at opposite ends and assembling the same upon a central tube to form a chamber. According to the present invention the manufacture of mufflers has been further simplified by forming the resonating chambers from a rolled tube having a rolled or welded seam and deforming the tube to'form necked portions forming resonating chambers about the central tube.

Thus an object of the invention is to provide resonating chambers for mufliers having integral side and end portions.

Another object of the invention is to provide a baflle in a muiiier construction in the form of a rolled tube having a welded or locked seam in which portions thereof have been deformed or necked so as to embrace the periphery of a central tube.

Still another object of the invention is the method of forming baiiles or the like between nested tubes.

A still further object of the invention comprises a method of providing a bafile or the like between nested tubes which comprises sizing an outer tube onto the periphery of the inner tube and overlapping the excess metal from the body of the outer tube.

These and other objects will be apparent from the following specification when taken with the accompanying drawings, in which Fig. 1 is a vertical section of a portion of a mufller illustrating an embodiment of the invention,

Fig. 2 is a section on the line II-II of Fig. 1,

Fig. 3 is a section taken on the line III-III of Fi Fig. 4 is a vertical section of a portion of a mufiler disclosing another embodiment of the invention,

Fig. 5 is a vertical section through the apparatus for necking a tube according to the present invention disclosing the necking blocks in separated position,

Fig. 6 is a perspective view of a single necking block,

Fig. '7 is a side elevation of the structure shown 5 in section in Fig. 5, showing a portion thereof in section, and

Fig. 8 is a vertical section similar to Fig. 5 showing the necking blocks in closed position.

Referring particularly to Fig. 1 of the drawings, 10 the reference character I indicates the outer shell of a portion of a mufller having embodied therein one form of the present invention. A head 2 having a connecting member 3 is connected to the shell I at one end thereof. Communicating with the connectingmember 3 is a tube 4 arranged to conduct at least a portion of the gases, the tones of which are to be attenuated. Disposed concentrically about a tube 4 is a second tube 5, which in the particular style of mufller g disclosed is supported from the shell'l by a bafiie 6.

As shown particularly in Figs 1, 2 and 3, the tube 5 has a necked portion 1 providing a restricted opening through the tube 5 which circumferentially engages the periphery of the tube 4.

The opposite sides 8 and 9 of the tube 5 are deflected out of alignment with the undefiectedportion of the body of the tube 5 into contacting engagement with the tube 4. As shown particularly in Fig. 2, the sides 8 and 9 each comprise an arcuate length equal to substantially one-half of the circumference of the tube 4. The excess metal of the tube 5 is folded upon itself to provide short flanges or corrugations ill and l I. It will 5 be observed that each of the flanges Ill and. II comprises two folds. The width of the flanges l0 and H is shown particularly in Figs. 1 and 3, and is determined by the width of the necking tools hereinafter described provided to deflect the sides 8 and 9 inwardly against the tube 4.

As shown in Fig. 1, the tube 4 is provided with a plurality of perforations I2 of any desired character to provide a. communication between the interior of the tube 4 and the interior of the tube 5. The necked portion '1 of the tube 5 produces in effect a baffle between the tube 4 and the tube 5 and provides resonating necks l3 and I4. It is to be understood that the position of the necked portion 1 may be wherever desired 5 and need not be in association with other structure such as the battle 6. For instance, two necked portions 20 and 2| in a tube 22, as shown particularly in Fig. 4, may be provided. The necked portions 20 and 2t circumferentially engage the periphery of a tube 23 corresponding to the tube 4. Between the necked portions 20 and 2| the tube 23 is provided with a plurality of perforations 24. The necked portions 20 and 2|, together with the portion of the tube 22 therebetween, form the walls of a resonating chamber 25, surrounding a portion of the tube 23 having therein the perforations 24. While the invention has been disclosed as applied to a particular style of mufller, it will be understood that the principles thereof need not be so limited, but may be utilized in mufilers having different arrangements of internal structure.

Figs. 5, 6, 7 and 8 disclose the structure for necking one tube about another. According to the present invention, as disclosed particularly in Fig. 5, a lower die 30 is mounted on a bed 3| and has cooperating therewith an upper die 32. The dies 30 and 32 have an internal bore 33 in which is arranged to be clamped the tube 5, onehalf of the bore 33 being in the die 30 and the other half thereof being in the die 32. The inner tube 4, on which the outer tube 5 is to be necked, is supported in some suitable manner in concentric relation to the outer tube 5. Between the ends of the dies 30 and 32 is provided a transverse slot 34, in which necking blocks 35 and 36 are arranged to slide. The necking blocks 35 and 36, as disclosed particularly in Fig. 6, are provided with an outer stopping flange 31 and an inner forming surface 38. The forming surface 38 has an arcuate portion having a radius equal to the radius of the outside surface of the inner tube 4 plus the thickness of the metal of the outer tube 5. The forming surface 38 is also provided with straight portions for forming the flanges l and l l, as disclosed particularly in Fig. 8. An eccentric 39 is provided for moving the upper die 32 downwardly into clamping engagement with the outer tube 5, and eccentrics 40 and 4! are provided for moving the necking blocks 35 and 36,

4| are then turned, and the die 32 and the necking blocks 35 and 36 backed off, and the apparatus is ready for another necking operation. During the inward movement of the necking blocks 35 and 36, the walls of the bore 33 deflect the excess of the body of the tube inwardly in the forming of the flanges l0 and ll so that the flanges l0 and H will always project outwardly only into alignment with the periphery of the undeflected tube 5. However, the amount of metal that is deflected inwardly in the forming of the flanges l0 and ii will depend somewhat upon the relative differences in diameter between the tubes 4 and 5.

The apparatus disclosed for necking one tube on another concentrically related thereto is not intended to be limiting, but is merely illustrative of one form of apparatus which may be used. It is also contemplated that the present invention be employed where the inner and outer tubes are not concentric. While in the drawings concentric tubes have been shown, it will be appreciated that the herein disclosed method can be carried out in connection with non-concentric tubes. For this reason in the claims the term .nested is used to indicate the location of tubes one within the other and covering both concentric and non-concentric tubes.

Having thus described my invention, what I desire to secure by Letters Patent and claim is: 1. In a mufiler of the character described. a pair of one piece rolled tubes in nested relation comprising an inner and an outer tube, said' outer tube having an inwardly extending portion intermediate its ends embracing the outer periphery of said inner tube throughout its entire circumference, that portion of said outer tube which is in excess of that embracing said inner tube being utilized in the form of corrugations.

2. In a mufliler of the character described, a pair of one piece rolled tubes in nested relation comprising an inner and an outer tube, said outer 

